Granulocyte macrophage colony stimulating factor (GM-CSF):

Stem cells obtained from the bone marrow are capable of giving rise to countable colonies of daughter cells in spleen. The growth factors were identified on the basis of their ability for colonial proliferation. Thus the name was assigned.

GM-CSF stimulates the proliferation of committed cells to form granulocyte and macrophages. It also stimulates proliferation for precursors of eosinophils, megakaryocytes and erythrocytes. In addition, it acts on the mature neutrophils, eosinophils, macrophages to enhance their effector responses.